This invention relates to automated injection devices for administration of liquid medicaments.
Automated injection devices enable patients to administer a dosage of liquid medicament for therapeutic purposes. An automated injection device may contain, for example, one or more liquid medicaments effective in treating anaphylactic shock caused by severe allergic reactions to foods, insect stings, and the like. An example of a liquid medicament suitable for treatment of anaphylactic shock is epinephrine. Automated injection devices that carry epinephrine are sometimes referred to as xe2x80x9cEPIxe2x80x9d injectors. Other types of injection devices may carry antiarrhythmic medicaments for administration during a heart attack, as well as antidotes to a variety of toxic agents, e.g., for military applications.
Most automated injection devices of this type are designed for single use in an emergency situation. For this reason, extended longevity usually is a requirement. In particular, such devices typically are constructed to contain a measured dosage of the liquid medicament in a sealed and sterile environment over an extended period of nonuse. The devices are designed for quick administration of the liquid medicament, often under the stress of shock. In many devices, a spring-loaded actuator facilitates automated injection without the need for significant manual intervention by the patient. The patient merely actuates a trigger that releases the spring-loaded actuator. The actuator drives a needle into the patient""s skin and quickly releases the liquid medicament. In this manner, there is no need for the patient to manually pierce the skin or operate a syringe for delivery of the liquid medicament. Often, the needle is not even visible to the patient.
The unpredictability of anaphylactic shock, heart attack, and other emergency medical conditions requires that the patient carry the automated injection device at all times. Unfortunately, the size and weight of many automated injection devices makes them cumbersome and inconvenient to carry. A number of carrying cases, holsters, belts, and the like have been devised to enhance the portability of automated injection devices. Still, the inconvenience associated with many devices causes users to disregard medical risks, and simply leave the automated injection devices at home. This is particularly the case for users engaged in active lifestyles involving high levels of physical activity.
The present invention is directed to automated injection devices for administration of one or more liquid medicaments, and methods for their use. A device in accordance with the present invention may be particularly useful for self-administration of liquid medicaments such as those used to treat anaphylactic shock, heart attack, exposure to toxic agents, or other emergency medical conditions.
A device in accordance with the present invention may include a number of features designed to reduce both the size and complexity of the device. With reduced size, the device may provide greater convenience and portability. Importantly, the reduced size may encourage more users to carry the device, and thereby reduce the risks associated with the medical conditions mentioned above.
With reduced complexity, the device can be constructed at a lower cost. Moreover, the device can be more reliable and simple to operate. In some embodiments, the device can be made from recycled and recyclable materials, reducing waste following use. The device preferably is made water-resistant to promote longevity and durability to environmental conditions. Also, in some embodiments, the device may be suitable for administration of liquid medicaments on a non-emergency basis, e.g., to administer insulin to diabetic patients.
In one embodiment, the present invention provides an automated injection device comprising a reservoir, a needle in fluid communication with the reservoir, a piston member with a piston face positioned within the reservoir, a spring adjacent the piston member, and a loading member that is movable to compress the spring, the loading member permitting the spring to expand following compression, whereby the expanding spring drives the piston member such that the piston face moves within the reservoir and expels the contents of the reservoir through the needle.
In another embodiment, the present invention provides an automated injection device comprising a housing having a first end and a second end, the housing defining an opening at the second end, a piston member slidably mounted within the housing, a reservoir slidably mounted within the piston member, a needle in fluid communication with the reservoir, a piston mounted within the piston member with a piston face positioned within the reservoir, a spring that bears against the piston member on a side of the piston member adjacent the first end of the housing, and a loading member oriented to drive the piston member toward the first end of the housing and thereby compress the spring, wherein the piston member and the loading member are configured to permit relative movement of the piston member and the loading member following compression of the spring, and the loading member defines a stop member that limits travel of the reservoir toward the second end of the chamber, whereby the spring drives the piston member relative to the loading member and toward the second end of the housing, and the piston member drives the reservoir against the stop member such that continued movement of the piston member relative to the reservoir drives the piston face through the reservoir and expels the contents of the reservoir through the needle.
In an added embodiment, the present invention provides a method for injection of a liquid medicament using a device having a reservoir, a needle in fluid communication with the reservoir, a piston member with a piston face positioned within the reservoir, a spring that bears against the piston member, and a loading member oriented to drive the piston member to compress the spring, the piston member and the loading member being configured to permit relative movement when the compressed spring reaches a sufficient level of spring force, wherein a portion of the loading member extends outward from the device, the method comprising pushing the loading member against a patient to drive the loading member into the device and toward the piston member, thereby compressing the spring, wherein the spring expands to drive the piston member relative to the loading member and extend the needle outward from the device and drive the piston face to expel the contents of the reservoir through the needle.
In a further embodiment, the present invention provides a method for injection of a liquid medicament using a device having a housing having a first end and a second end, the housing defining an opening at the second end, a piston member slidably mounted within the housing, a reservoir slidably mounted within the piston member, a needle in fluid communication with the reservoir, a piston mounted within the piston member with a piston face positioned within the reservoir, a spring that bears against the piston member on a side of the piston member adjacent the first end of the housing, and a loading member oriented to drive the piston member toward the first end of the housing and thereby compress the spring, wherein the piston member and the loading member are configured to permit relative movement when the compressed spring reaches a sufficient level of spring force, the loading member defines a stop member that limits travel of the reservoir toward the second end of the chamber, and a portion of the loading member extends outward from the opening, the method comprising pushing the loading member against a patient to drive the loading member into the device and toward the piston member, thereby compressing the spring, wherein the spring expands to drive the piston member relative to the loading member and extend the needle outward from the opening and drive the piston face to expel the contents of the reservoir through the needle.
In another embodiment, the present invention provides an automated injection device comprising a reservoir, a needle in fluid communication with the reservoir, a piston member with a piston face positioned within the reservoir, a spring adjacent the piston member, and a loading member that is movable to compress the spring and permit the spring to expand following compression, the expanding spring driving the piston member such that the piston face moves within the reservoir and expels the contents of the reservoir through the needle, wherein the piston member and the reservoir partially overlap along a longitudinal extent of the device and are sized such that the device has a length of less than or equal to approximately 3.0 inches and a width of less than or equal to approximately 2.0 inches.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.